Clonidine enhances delayed matching-to-sample performance by young and aged monkeys.

Clonidine, an alpha-2 noradrenergic agonist, has been shown to alter cognitive performance in humans and animals. Included among the evidence are studies which differ in their conclusions regarding the question of whether clonidine administration improves delayed response (DR) performance by nonhuman primates. The present results indicated that clonidine administration to both young and aged monkeys results in a modest performance improvement as measured by one of the commonly employed versions of DR performance-delayed matching-to-sample (DMTS). The clonidine-induced enhancement of DMTS had a duration of at least 24 h in both age groups.